LNG land bridge

ABSTRACT

An endless chain of elongated vehicles, each carrying a thermally insulated sealed container for liquefied gas (LNG) traveling at high speed along a guideway between loading and unloading locations. A folding mechanism turns vehicles into dense vertical side-by-side relationship for loading and unloading at low speed, similar to filling bottles by conventional bottling machines. Containers are connected to piping which recovers and returns in transit re-gasified LNG for re-liquefaction. Containers are capable of holding gas under pressure in case of extended conveyor stoppage. High vehicle speed is enhanced with magnetic levitation suspension and linear induction motor propulsion.

BACKGROUND OF THE INVENTION

The present invention relates to design and construction of an endless chain of elongated vehicles, each carrying an elongated sealed container for liquefied gas (LNG). More specifically it relates to vehicle and container design, method of loading, unloading and transporting LNG safely and without undue re-gasification or boil-off loss in transit. Furthermore, container design and attached piping feature recovery and recycling of in transit re-gasified fluid. In general, liquefaction plants liquefy gas by cooling it to below −260° F. (−160° C.). Elongated containers are then dynamically loaded with LNG while in side-by-side upright position, similar to filling bottles by conventional bottling machines. Thereafter, containers are sealed, rotated by their vehicles into horizontal end-to-end position and rapidly transported to their destination where they are returned into the same side-by-side upright position for unloaded. Any in transit re-gasified LNG, which may occur during extended conveyor stoppage is recovered and returned for re-liquefaction by a to vehicles attached flexible endless gas return pipeline.

SUMMARY OF THE INVENTION

The present invention provides the ability to carry LNG by a conveyor of a type having in a closed loop an endless string of elongated vehicles containing cylindrical containers traveling at relatively high rate of speed between a loading end and an unloading end, vehicles with containers being folded into dense vertical side-by-side relationship at relatively low rate of speed for loading at a loading end and for unloading at an unloading end. Containers are heat insulated and can carry contents under pressure. When in densely folded upright relationship, vehicles with containers reveal two access ports, one at the top for fluid loading and unloading, and one on the side for returned gas release. Containers are equipped with safety pressure release valves, which are connected to an attached endless flexible gas return pipe. Discharge of gas from containers is returned for re-liquefaction by a flexible gas return pipe. The box-shaped vehicles have suspension, guidance and propulsion means for high-speed travel along guideways. Vehicles are paired and coupled together by couplings so that two adjacent access ports face each other. There are two types of couplings, one with wing-like cam followers near their upper edge, which are located at the access port ends of the vehicles, and one with wing-like cam followers near their bottom edge, which are located at the opposite ends of the vehicles. Vehicles have attached on each side a row of permanent magnets magnetized in vertical direction. High-speed sections of the guideway consist of up-facing U-shaped channels having near the top of each channel leg matching rows of permanent magnets magnetized in opposite direction to those on vehicles. Suspension of vehicles thus occurs by magnetic repulsion between vehicle magnets and guideway magnets. Dual guide channels in guideway and guideway followers on the vehicles provide lateral guidance. Propulsion is by linear induction motors, the primary of which is located at intervals in the bottom center of the U-shaped guideway channel. The underside of vehicles is covered by platens, which act as linear motor secondary. The cam followers on the couplings engage stationary dual cams before and after each loading and unloading location whereby vehicles are rotated from end-to-end relationship to side-by-side relationship and back. While in side-by-side relationship, vehicles are held against, and rotate with, loading and unloading carousels, at which time containers and the flexible gas return line is accessed for loading and unloading. The flexibility of the endless gas return pipe allows it to bend with containers when they fold and unfold at loading and unloading ends. Said LNG conveyor comprising:

(a) means for carrying LNG in heat insulated pressure containers;

(b) means for dynamic loading and unloading containers;

(c) means for in transit re-gasified LNG to be recovered for re-liquefaction;

(d) means for guiding and propelling containers along guideways.

The present invention is intended to enable transportation overland of LNG in large quantities, similar to what is already commonly done by ship at sea. The advantage of liquefaction is that gas volume is thereby reduced by a ratio of about 620 to one. While LNG ships take many days for a single delivery, they have on board refrigeration machines to prevent re-gasification of their cargo. Re-gasification expands LNG back to its original volume, except when it is confined in pressure containers. The present invention has no refrigeration machines traveling with its containers. Instead it relies on delivering LNG at high rate of speed, thereby leaving very little time for temperature increase and LNG re-gasification in transit. To enable high speed, means of suspension consist of permanent magnets in repulsion, and means for propulsion consist of linear induction motors.

Large quantities of stranded natural gas in remote regions could be brought as LNG to market with this invention, for example, from the North Slope of Alaska for a distance of 800 miles (1,300 Km) to a shipping port in the south of Alaska. With a line speed of 200 miles/hour (320 Km/hour), containers would be exposed for four hours to LNG re-gasification inducing surroundings, which with pre-cooling of LNG to lower than re-gasification temperature and with good insulation would keep heat intrusion and re-gasification to a minimum. However, the present invention provides that any emitted gas due to re-gasification and excessive container pressure would be recovered and returned for re-liquefaction by the endless flexible gas return pipe to which all containers are connected. No gas would be released to the outside.

For a shorter application, the present invention could also be used as an LNG Land Bridge across Panama similar to what already exists there for crude oil. Many new LNG ships are now also too large to fit through the Panama Canal. LNG re-gasification while in transit may also be reduced or even totally avoided by (1) pre-cooling containers before filling, (2) filling containers only partially and (3) replacing long conveyors with shorter ones interspaced with liquefaction booster plants.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a plan view of an LNG Land Bridge.

FIG. 2. shows a longitudinal section of a vehicle with LNG container.

FIG. 3 shows a cross-section of a vehicle with LNG container and linear motor.

FIG. 4 shows a side view of a vehicle with connecting links, cam followers and linear motor.

FIG. 5 shows vehicles being folded and unfolded by cams.

FIG. 6 shows a partial cross-section through a loading carousel.

FIG. 7 shows a partial cross-section through an unloading carousel.

FIG. 8 shows prior art of an elevated view of an LNG Land Bridge construction by helicopter.

FIG. 9 shows prior art of a triangular truss support structure for an LNG Land Bridge.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a plan view of a typical LNG Land Bridge 1. Being temporarily attached to carousel 2, an endless succession of container-carrying vehicles progress slowly through loading end 3 in dense upright side-by-side relationship being filled with LNG through ports at their tops. Assuming carousel 2 is rotating clockwise in FIG. 1, containers are rotated in a vertical plane in deceleration section 4 from a horizontal end-to-end relationship to an upright side-by-side relationship. The reverse vertical rotation occurs in acceleration section 5. Thereafter, vehicles carrying LNG filled containers are propelled at high speed along guideway 6 and empty returns are propelled at high speed along guideway 7. Arriving for discharge, vehicles with filled containers are again rotated in a vertical plane into dense upright side-by-side relationship in deceleration section 8. Vehicles are unloaded through ports at their tops, while being temporarily attached to carousel 9, at unloading end 10. Thereafter, vehicles are again unfolded in acceleration section 11.

FIG. 2 shows a longitudinal section of vehicle 12 exposing the therein-located LNG container 13 embedded in thermal insulation 14. Container 13 has an internal filling and emptying tube 15 with an access port 16 at the top for loading and unloading of LNG. Tube 17 connects container 13 to the inlet side of pressure release valve 18. Tube 19 connects the outlet side of pressure release valve 18 to endless flexible gas return pipe 20. The flexibility of gas return pipe 20 allows it to bend with vehicles 12 as they fold and unfold during speed change. Gas return pipe 20 has an access port 21 at a uniform location on each vehicle 12 for unloading returned gas.

FIG. 3 shows a cross-section of high-speed guideway sections 6 and 7. Vehicle 12 has in the center on each side from end-to-end wing-like lateral extensions 22. Imbedded in lateral extensions 22 flush with their underside surfaces are rows of permanent magnets 23 magnetized in vertical direction. Directly underneath magnets 23, in close proximity and magnetized in opposite direction to those on vehicles 12, are matching permanent magnets 24 attached to the tops of the sides of open at the top guideway channel 25. Magnets 23 on vehicle 12 and magnets 24 in guideway channel 25 are magnetically repelling each other vertically and thereby cause magnetic levitation of vehicle 12. Attached at the bottom corners of vehicle 12 and facing outwards are periodically adjustable self-lubricating plastic sliders 26. Imbedded in the sides of guideway channels 25, opposite sliders 26 and facing inwards, are recessed guide channels 27. Sliders 26 are in sliding engagement with guide channels 27, thereby providing lateral guidance. Located centrally underneath vehicle 12 and attached at intervals to guideway channel 25 is primary winding 28 of linear motor 29. Attached to the underside of vehicle 12 and held in close proximity above linear motor primary winding 28 is linear motor secondary 30 in the form of a platen extending the full length of vehicle 12.

FIG. 4 shows a side view of vehicles 12 in end-to-end alignment connected to each other by couplings 31 and 32 with linear induction motor 29 underneath. Coupling 31 has on each side laterally extending wing-like cam followers 33 at its top edge, alternating with coupling 32, which has laterally extending wing-like cam followers 34 at its bottom edge. Pins 35 connect couplings 31 and 32 to vehicle 12, whereby adjacent vehicles 12 can be folded into dense side-by-side relationship and back to end-to-end relationship. Containers 13 are oriented in alternating directions in vehicles 12 so that two adjacent access ports 16 are facing each other at coupling 31 and their closed ends facing each other at coupling 32.

FIG. 5 shows an illustration of how diverging and converging cams cause the continuous folding and unfolding of vehicles 12 in acceleration sections 5 and 11 and in deceleration sections 4 and 8. Assuming direction of motion in FIG. 5 from left to right, on arrival in end-to-end relationship wing-like cam followers 33 engage and follow dual upper cams 36, and wing-like cam followers 34 engage and follow dual lower cams 37. Cams 36 and 37 end at the point where vehicles 12 are densely folded against each other, which is also the point where loading or unloading starts.

FIG. 6 shows the right half of a cross-section of carousel 2 depicting the loading operation as occurring at loading end 3. LNG is flowing through stationary intake pipe 38 to, and thereafter downward, along the center of rotation 39 of carousel 2. From there it flows on through swivel coupling 40 into header 41 which is attached to, and rotates with, carousel 2 at an elevated location. Down-sloping pipes 42 connect header 41 with loading nozzles 43, one for each container 13. Concurrently with the LNG loading operation, gas from gas return pipe 20 is released through temporary connection to access port 21 into pipe 44 and from there to the center of rotation 39 and through swivel coupling 45 into stationary discharge pipe 46 for re-liquefaction.

FIG. 7 shows the right half of a cross-section of carousel 9 depicting the unloading operation as occurring at unloading end 10. LNG arrives under pressure in containers 13. Unloading nozzles 47 make contact with access port 16 at each container 13. Induced pressure differential forces LNG out of containers 13 through internal filling and emptying tube 15. Down-sloping pipes 48 transmit the LNG to header 49 at the center of rotation 50, and from there through swivel coupling 51 to stationary discharge pipe 52, which is connected to the suction sides of pumps which forward the LNG to storage and shipping facilities. Concurrently with the LNG unloading operation, gas from gas return pipe 20, if present, is released through temporary connection to access port 21 into pipe 53 and from there to the center of rotation 50 and on through swivel coupling 55 into stationary discharge pipe 56 for re-liquefaction.

FIG. 8 shows prior art of construction by helicopter of an elevated guideway support structure required for an LNG Land Bridge. It has a continuous cable suspended triangular truss, which is needed to hold the LNG Land Bridge guideways in smooth alignment in straight-aways, vertical curves, banked horizontal curves and transitions in between, enabling the passing at high speed over rugged terrain and high mountains.

FIG. 9 shows prior art of details of an elevated triangular truss support structure with a loaded vehicle guideway and empty return vehicle guideway on top.

The best mode of carrying out the present invention is as follows:

-   -   1. Elect capacity, design physical components for the elected         capacity and perform full size tests.     -   2. Erect an elevated triangular truss support structure along         the route and attach the LNG Land Bridge to its top.     -   3. Constructs LNG supply facilities at the loading end of the         LNG Land Bridge,     -   4. Construct LNG shipping facilities at the unloading end of the         LNG Land Bridge. 

1. A method for transporting liquefied gas (LNG) between loading and unloading locations in end-to-end connected elongated thermally insulated sealed container carrying vehicles, guided and propelled in a closed loop having vehicle folding and unfolding means to achieve a low rate of speed for loading and unloading, and a high rate of speed in-between.
 2. A method of claim 1 wherein incidentally re-gasified portions of LNG from containers and incidentally to loading and unloading emitted gas is recovered for re-liquefaction.
 3. A method of claim 2 wherein containers are connected through pressure release valves to an attached endless flexible gas return pipe.
 4. A device for transporting liquefied gas (LNG) between a loading and unloading location in end-to-end connected elongated thermally insulated sealed container carrying vehicles, guided and propelled in a closed loop having vehicle folding and unfolding means to achieve a low rate of speed for loading and unloading, and a high rate of speed in-between, said device comprising: (A) each vehicle providing for guidance, propulsion, controls and connection to adjacent vehicles; (B) containers in vehicles having gas and LNG access port for mating with loading and unloading nozzles at loading and unloading locations; (C) means at loading and unloading locations for supplying to, and withdrawing from, containers through flexible temporary hookups gas and LNG.
 5. A device of claim 4 wherein incidentally re-gasified portions of LNG from containers and incidentally emitted gas during filling and discharge is recovered for re-liquefaction.
 6. A device of claim 4 wherein containers are connected through pressure release valves to an attached endless flexible gas return pipe. 